Electric connector plug construction



May 26, 1959 c. E. GILBERT ELECTRIC CONNECTOR PLUG CONSTRUCTION Original Filed April '7, 1950 2 Sheets-Sheet 1 T .m 5 7 mm M 4/ a M via E. W m A 1 1 w W z 5 a, 4 w E. m M 4 5 a, a r 4.? Z .W\\\\\\- A 0 F /4 6 5 WW. Z 4 0 ATTORNEYS y 1959 c. E. GILBERT 2,888,659

ELECTRIC CONNECTOR PLUG CONSTRUCTION Original Filed April 7, 1950 2 Sheets-Sheet 2 IN V EN TOR.

ew haw ATTORNEYS CHARLES E. GILBERT United States Patent Ofitice 2,888,659 Patented May 26, 1959 ELECTRIC CONNECTOR PLUG CONSTRUCTION Charles E. Gilbert, New York, N.Y.; Edwin J. Fluss, Margaret Doris Gilbert and Norman Coates, executors of said Charles E. Gilbert, deceased Original application April 7, 1950, Serial No. 154,500, now Patent No. 2,700,206, dated January 25, 1955. Divided and this application May 17, 1954, Serial No. 430,463

3 Claims. (Cl. 339-99) application Ser. No. 154,500, filed April 7, 1950, now

Patent No. 2,700,206, granted January 25, 195-5, for Method of Fabricating Electric Plugs.

The conventional plug receptacle or outlet is adapted:

to cooperate with a plug having a pair of fiat parallel prongs extending perpendicularly with respect to the wall or other mounting of the receptacle. In conventional plugs, the conductor cord is connected to the plug in alignment with its prongs, and extends perpendicularly from the wall on which the receptacle is mounted. This creates an unsightly appearance and an inconvenient arrangement, since in an exposed location the projecting conductor cord may be subject to physical contact with movable objects.

According to one aspect of the present invention, this disadvantage is overcome by having the conductor cord extending perpendicularly to the prongs of the plug, so that upon inserting the plug in the receptacle the conductor 'cord will extend generally parallel to and only slightly spaced from the wall supporting such receptacle.

According to another aspect of the present invention a simplified method of constructing 'such plugs and of connecting them to conductor cords is provided. Ac-

cording to this feature of the invention, the plug is formed of only three parts, two of which are identical. These parts are a shell or housing molded of suitable insulating material, and a pair of contact members terminating at one end, in suitable prongs adapted for cooperation with a receptacle. The shell is provided with a pair of slots into which the contact members slidably fit. The conductor cord is then placed over the projecting ends of the contact members opposite their prong ends without having its conductors in any. way separated or the insulation stripped therefrom. The apparatus as thus assembled is then placed in a molding machine where simultaneously the conductor cord wires are placed in electrical contact with the respective contact members, and the conductor cord is molded into the shell. This is done by the use of thermosetting insulating material rather than thermoplastic material, which up tonowv has been exclusively used in this art, providing increased simplicity of apparatus, as Well as a shorter cycle of operation, permitting greatly increased production from a given machine. This shorter cycle of operation stems from two features of the present invention. First, the shell is prefabricated and only a slight amount of molding is necessary duringthe assembly operation, and, second, the use of thermosetting material eliminates the former period of curing and cooling necessary for the most clearly in Figure 6. In addition,

2 conventional thermoplastic material previously used in this art.

The present invention also provides a simplified apparatus for carrying out the method and producing the structure briefly described above.

Further objects and advantages of the present. invention will be more clearly apparent from the following specification taken in conjunction with the appended drawings, in which Figure 1 is a side elevation view of a preferred form of completed plug arrangement connected to a conductor cord;

Figure 2 is an end elevation view of the structure of Figure I viewed from the conductor end thereof;

Figure 3 is a side elevation cross sectional view of the device of Figures 1 and 2 taken along the line 3-3 of Figures 2 and 4;

Figure 4 is a transverse cross sectional view taken along line 4-4 of Figures 1 and 3;

Figure 5 is a side elevation crosssectiona-l view of the shell and contact members forming a sub-assembly of the structure of Figures 1-4 before the conductor cord is assembled therewith;

Figure 6 is a fragmentary transverse cross sectional view of the structure of Figure 5 along line 6-6 thereof;

Figure 7 is a top view of the structures of Figures 5 and 6;

Figure 8 is a developed view of the contact element of the previous figures;

Figure 9 shows in simplified form apparatus for assembling the plug and conductor cord, in open position;

Figure 10 shows the apparatus of Figure 9 in closed position during which the molding operation is etfected;

Figure 11 is a transverse cross sectional view of the i lower member of the apparatus of Figures 9 and 10 taken along line 11-11 of Figure 9;

Figure 12 is a bottom view of the upper member of Figure 9 viewed along the line 12-12 thereof; and

Figure 13 is a top view of the lower member of Figure 9 viewed along the line 13-13 thereof.

Referring to Figures 1 to 4, there is shown the completed and assembled connector plug and conductor cord arrangement forming the present invention. As shown, the conductor cord 21 is assembled in the plug body 22 with the wires of the conductor cord 21 in respective electrical contact with the contact members 23, 24 termi nating in respective prongs 26, 27 adapted to make electrical contact with the contact members of any conventional plug receptacle or outlet.

As is clear from these figures, the entire assembly consists of I but three parts in addition to the conductor cord 21, namely the plug body 22 and the two identical contact members 23, 24. The structure of each of these contact members is shown more clearly in Figure 8. Each contact member 23, 24 is formed. from a single strip 30 of conductive material such as brass, having a pair of sharp points 28 at one end and a single point 2 9 at the other end, the strip 30 being folded about line 31 to form a doubled prong end 26 or 27. When so folded, the point 29 registers just between the points 28 as shown adjacent the points 28 is a tab portion which is bent at right angles to the strip 30 about a line 33 to form a locating ear or lug 3 2, such as shown in Figures 3 or 5. A pair of apertures 34 are formed symmetrically about the folding line 31 so as to be in register, after the contact member is doubled over as shown on Figures 2 and 4. These apertures 34 form a type of detent for the prongs 26, 27 when seated in the plug receptacle.

In addition, reinforcing ribs are formed into the strip 27 in the form 'of' a pair of parallel ribs 36 at one side of the fold line 31 and a single rib 37 on the other side.

These ribs extend symmetrically for equal distances on opposite sides of the fold line 31 and the rib 37 seats between the ribs 36. As shown in Figures 2 and 6, these ribs 36, 37 extend partially within the plug body 22 and partially outside the plug body 22 to stiffen the prongs 26, 27 and prevent them from readily bending relative to the plug body 22. This arrangement of ribs provides greatly improved strength for the prongs Without substantially increasing the thickness of the finished prong, and permits the use of thinner conductive material for the fabrication of the prongs where desired.

The plug body 22 is shown more clearly in Figures and 7, and comprises a generally rectangular body undercut at its ends as shown at 38 and 39 and also cut away at its center as shown at 40. These cut away portions 38, 39 and 40 leave the plug body with a pair of thin lower side walls 41 and lower end walls 42, 43 of greater thickness, all of these walls extending from the upper portion 44 of the plug body which is formed with upper side walls 46 and 47 constituting extensions of the side walls 41 and each having a lip 45 forming a finger hold for grasping the plug body when removing it from a plug receptacle.

The upper end wall 50 joins the upper side walls 46 and 47 at one end, the other end wall being omitted. The upper part 44 of the plug body 22 therefore forms a conductor-cord-receiving channel 51 with a depressed center 49, and the inner surfaces of the side walls 46 and 47 are provided with a plurality of projections shown at 48 which serve to engage the sides of the conductor cord to inhibit movement of the conductor cord relative to the plug body.

The thicker lower end walls 42, 43 of the plug body 22 are provided with respective slots extending completely therethrough from top to bottom, in each of which one of the folded contact members 23, 24 is adapted to be inserted from the upper end into the position shown most clearly in Figure 5, with the tabs 32 facing one another and seated against the depressed center 49 of the channel 50 in the upper portion of the plug body. When this is done the respective points 28, 29 of the two contact members 23, 24 lie in opposite sides of the channel 50. The tabs 32 prevent the contact members 23, 24 from moving downwardly and, as will be shown, further means are provided for preventing upward movement of these contact members so that they are then rigidly secured to the remainder of the structure.

The assembling apparatus shown in Figure 9 has an upper mold portion 52 with a recess closely conforming to the shape of this sub-assembly. The lower mold portion is formed in two portions, one portion 54 having a rectangular channel 53 extending therethrough of a width substantially equal to the width of the channel 50 and a length substantially equal to the length of the plug body 22, as shown in Figure 13. Slidably mounted in this channel 53 is a rectangular insert 55 having a cross section closely conforming to the channel 53 and terminating at its upper end in a concave cylindrical surface 57. The rectangular insert 55 is normally below the upper edge 58 of the lower molded portion 53 by an amount so selected that a proper volume of thermosetting molding powder will be retained in the recess formed by the channel 53 and the rectangular insert 55.

In assembly, the combination of plug body and control members is placed in the upper mold recess, and the recess in the lower mold portion is filled with thermosetting molding powder. Then a conductor cord end is held in channel 50 of the plug body while the mold members 54 and 55 are moved upwardly together until the upper surface 58 of the lower mold Portion 54 seats firmly against the lower surface 59 of the upper mold portion 52. During this time heat is applied to both mold members in any suitable manner. For example, one such suitable manner is shown in my copending application Serial No. 641,519, filed January 16, 1946,

for Machine for Making Molded Plug Bodies for Electrical Connectors. The heat is applied simultaneously with pressure, which forces the rectangular insert 55 of the lower mold portion upwardly against the plug body 22 in the upper mold portion 52.

Normally a temperature of approximately 300 F. exists at the location of the plug body 22 and a pressure of approximately 2000 pounds per square inch is applied by the rectangular insert 55. These values are not highly critical, since temperatures from 300 to 350 F. may be used and pressures from 850 pounds per square inch and up may be used, the sole criterion being that at the pressure and temperature used, the thermosetting powder will fuse and join with the plug body 22 to provide an integrally molded cap for the plug body such as shown at 61 in Figures 1 to 4.

It will be understood that the pressure applied by the rectangular insert 55 also forces the conductor cord 21 against the points 28 and 29 of the respective contact members 23, 24, which points thereupon pierce the insulation of the conductor cord 21 and make permanent electrical contact with the respective wires of the conductor cord 21. Also the molding temperature is sulficiently low so that no harmful efiects are produced on the insulation of the conductor cord 21.

It will be understood, however, that where desired, an intermediate step might be utilized whereby the conductor cord 21 is forced on to the points 28 and 29 either before the plug and contact assembly is placed in the upper molded portion 52 or after such placement but before the lower molded portion closes upon the upper molded portion 52.

By these methods only a slight amount of molding is performed during assembly. The molding material contained in the recess 69 not only provides the cap 61 but fills all the interstices between the conductor cord and the plug body 22 and integrally joins with the material of the plug body 22 to rigidly maintain the conductor cord in operative position relative to the contact members. Both the projections 48 (Figure 7) and the surrounding of the conductor cord by molding material serve to retain the conductor cord within the plug body against even strong pulls which might be encountered in use.

It will be understood that both the prongs and the plug shells can be fabricated readily by adaptations of known automatic machinery and the sub-assembly of the plug body and contacts such as shown in Figure 5 can also be made automatically, thereby facilitating and speeding up production of the completed plug and cord assemblies.

The number of parts of this plug and cord construction are thereby maintained at a minimum including merely the cord, the plug body and the two identical plug contacts. Fabrication is greatly simplified and assembly is accomplished in a minimum number of steps performable by relatively low skilled labor, whereby not only is production speeded up, but the cost of the completed construction is greatly minimized.

While the above plug and cord construction and the methods of and apparatus for fabricating the same have been described in detail with respect to preferred embodiments thereof, it is to be understood that the above description is illustrative only and is not to be taken in a limiting sense, since many apparently widely divergent constructions, methods and apparatus can readily be devised by persons skilled in this art without departing from the spirit of the present invention which is defined solely by the appended claims.

What is claimed is:

l. A unitary connector plug and cord arrangement comprising a rigid insulating shell having a pair of parallel contact-element-receiving channels extending completely therethrough, and a single rectilinear conductor-cordreceiving channel extending transversely of and interconnecting said first channels, said cord-receiving channel being adjacent one edge of said shell and having cordretaining corrugations along the sides thereof, a pair of identical contact elements, each formed of a doubledover conductive strip providing a receptacle-mating prong at one end and an insulation piercing point at the other end adjacent one side edge of said strip, each of said elements being positioned in a respective elementreceiving shell channel with its point projecting into said cord-receiving channel adjacent a respective side thereof, a conductor cord lying in said channel in engagement with said corrugations with said element points piercing the insulation thereof and making electrical contact with the respective wires of said cord, and a rigid insulating cap fused to said shell and keyed to said corrugations and covering said cord and filling said cord channel, to provide a unitary plug and cord arrangement, said corrugations retaining said cord against longitudinal pulls thereon.

2. A unitary connector plug and cord arrangement comprising a rigid elongated insulating shell having a pair of contact-element-receiving channels extending completely therethrough and a single rectilinear conductor cord-receiving channel extending transversely of and communicating with said first channels, said conductor-cord-receiving channel having a plurality of projecting ridges formed longitudinally on the side walls thereof, a pair of identical contact elements each formed of a conductive strip providing a receptacle-mating prong at one end and an insulation piercing point at the other end, each of said elements being positioned in a respective element-receiving channel of said shell with its point projecting into said cord-receiving channel, and with its prong extending beyond said contact-element-receiving channel, a conductor cord lying in said channel with said element points piercing the insulation thereof and making electrical contacts with the respective wires of said cord, said conductor cord being retained within said receiving channel by said retaining ridges, and a rigid insulating cap fused to said shell and covering said cord and filling said cord channel to provide a unitary plug and cord arrangement.

3. A unitary connector plug and cord arrangement comprising a rigid elongated insulating shell having a pair of contact-element-receiving channels and a single rectilinear conductor cord-receiving channel communicating with said first channels, said cord-receiving channel having cord-retaining corrugations in the side walls thereof, a pair of contact elements each formed of a conductive strip and having a receptacle-mating prong at one end and an insulation piercing point at the other end, each of said elements being positioned in a respective element-receiving channel of said shell with its point projecting into said cord-receiving channel, a conductor cord lying in said channel with said element points piercing the insulation thereof and making electrical contact with the respective wires of said cord, said cord being retained by said side-wall cord-retaining corrugations, and a rigid insulating cap formed integrally with said shell and covering said cord and filling said cord channel to provide a unitary plug and cord arrangement.

References Cited in the file of this patent UNITED STATES PATENTS 2,159,064 Walter May 23, 1939 2,181,575 Chirelstein Nov. 28, 1939 2,206,714 Benander July 2, 1940 2,506,620 Sundt May 9, 1950 2,647,245 Gilbert July 28, 1953 2,700,206 Gilbert Jan. 25, 1955 

